The present invention relates to a variable displacement swash-plate type compressor which is particularly available as a refrigerant compressor for an automotive air-conditioning apparatus.
As a conventional displacement control for a compressor, for instance, as shown in Japanese Patent Unexamined Publication No. 58-162780 there have been known a swash-plate type in which a swash plate is provided on a rotary shaft of the compressor so that a change in inclination angle of the swash plate causes the reciprocating stroke of each piston to change.
However, a rotational center of the swash plate of the conventional swash-plate type compressor is kept constant, and the inclination angle of the swash plate is only changeable about a predetermined rotational center. For this reason, in the conventional displacement control, although the reciprocating stroke of each piston is changed in accordance with the inclination angle change of the swash plate, dead volumes would be increased in two working chambers in contact with opposite end faces of the piston. Thus, the compressor of this type is not suitable for compressing a refrigerant and the like which are compressible fluids.
In view of the foregoing problem inherent in the prior art, the present inventors et al have proposed an improved swash-plate type compressor in U.S. application Ser. No. 147,036 filed on Jan. 20, 1988, which is a CIP application of a parent application filed on Sept. 1, 1987.
In that compressor, a support portion for supporting the rotational center of the swash plate is provided to be shiftable relative to a rotary shaft of the compressor in the axial direction thereof, whereby the rotary center position of the swash plate may be shifted simultaneously with the inclination angle change thereof. With this structure, each piston of the compressor is moved so that the position of a top dead center in each working chamber formed on one side of the piston is kept substantially constant irrespective of the change in inclination angle of the swash plate. As a result, the suction and compression of a fluid can be performed in the working chamber to avoid the generation of large dead volume.